Examples of natural red pigments applicable to food products include red cabbage pigment extracted from red cabbage leaves, gardenia red pigment extracted from gardenia fruits, cochineal pigment extracted from cochineal insects, paprika pigment extracted from paprika fruits, beet red extracted from beet root, grape skin pigment extracted from grape skin, and monascus pigment extracted from microorganisms of the genus monascus. These pigments exhibit their own unique color tones but have mutual disadvantages. That is, the color tone may vary according to the pH, and some pigments lack stability to oxidation.
Similarly, heme pigment as the body of red pigment in meat and whale meat is unstable to oxidation and easily converted to the met form on heating, for example. One and only means for preventing conversion of heme pigment to the met form on heating is to coordinate nitrogen monoxide at the sixth coordination site of the heme central iron atom to thereby nitrosate the heme pigment. For this purpose, it is allowed to use a color fixative, e.g. sodium nitrite, which is a nitrogen monoxide supply source, in meat products and whale meat products. Nitrosated heme pigment is stable to oxidation even after it has been heated, and has an excellent color tone of pinkish red.
However, nitrite is a substance exhibiting very high reactivity, which oxidizes reducing substances and causes nitrosation, diazotization and deamination. Particularly, nitrosoamine formed by reaction of nitrite with secondary amine has strong carcinogenicity. Therefore, the use of nitrosoamine is regarded as questionable.
The present invention was made in view of the above-described circumstances, and an object of the present invention is to provide a natural red pigment stable to oxidation and exhibiting an excellent color tone and also provide food products and food materials that are colored with the natural red pigment. Another object of the present invention is to provide meat products, whale meat products, fish meat products and fish paste products that are stable to oxidation and exhibit an excellent color tone without the need to use a color fixative, e.g. nitrite.